我查看了您的代码，并在空数据库上运行了数据库迁移。你的迁移似乎没有问题。但是，在你的错误中的这一行：

  PG ::错误：错误：关系用户已经存在
 

表明您可能没有使用全新的数据库。假设您没有任何关键任务存储在数据库中的数据，***的办法就是放弃数据库并重新开始。所以，如果你运行：

  heroku pg：reset blog_production 
 

（假设您正在以生产模式进行部署），您将拥有全新的数据库。然后只需要：

  heroku run rake db：migrate 
 

，你应该回到正轨。

Is deploying to Heroku typically like pulling teeth? I've been trying for a week now and it's error after error. I've contacted Heroku support and they suggested I try ***. So here it goes.

I've just upgraded my Devise to 2.0 schema following the guide: https://github.com/plataformatec/devise/wiki/How-To:-Upgrade-to-Devise-2.0-migration-schema-style .

See the codebase here: www.github.com/apane/blogit_blog

I now have the following error (this should be the last of em')

-- create_table(:users)
NOTICE:  CREATE TABLE will create implicit sequence "users_id_seq1" for serial column "users.id"
rake aborted!
An error has occurred, this and all later migrations canceled:

PG::Error: ERROR:  relation "users" already exists
: CREATE TABLE "users" ("id" serial primary key, "email" character varying(255) DEFAULT '' NOT NULL, "encrypted_password" character varying(255) DEFAULT '' NOT NULL, "reset_password_token" character varying(255), "reset_password_sent_at" timestamp, "remember_created_at" timestamp, "sign_in_count" integer DEFAULT 0, "current_sign_in_at" timestamp, "last_sign_in_at" timestamp, "current_sign_in_ip" character varying(255), "last_sign_in_ip" character varying(255), "created_at" timestamp NOT NULL, "updated_at" timestamp NOT NULL) /app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:650:in `exec'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:650:in `block in execute'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:280:in `block in log'
/app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.2.13/lib/active_support/notifications/instrumenter.rb:20:in `instrument'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract_adapter.rb:275:in `log'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/postgresql_adapter.rb:649:in `execute'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/schema_statements.rb:170:in `create_table'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:466:in `block in method_missing'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `block in say_with_time'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:438:in `say_with_time'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:458:in `method_missing'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:334:in `method_missing'
/app/db/migrate/20130529023532_devise_create_users.rb:3:in `up'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:370:in `up'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:410:in `block (2 levels) in migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:410:in `block in migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/connection_pool.rb:129:in `with_connection'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:389:in `migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:528:in `migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:720:in `block (2 levels) in migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `call'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `block in ddl_transaction'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/connection_adapters/abstract/database_statements.rb:192:in `transaction'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/transactions.rb:208:in `transaction'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:775:in `ddl_transaction'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:719:in `block in migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:700:in `migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:570:in `up'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/migration.rb:551:in `migrate'
/app/vendor/bundle/ruby/1.9.1/gems/activerecord-3.2.13/lib/active_record/railties/databases.rake:193:in `block (2 levels) in <top (required)>'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `call'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:246:in `block in execute'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:241:in `execute'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:184:in `block in invoke_with_call_chain'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:177:in `invoke_with_call_chain'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/task.rb:170:in `invoke'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:143:in `invoke_task'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block (2 levels) in top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `each'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:101:in `block in top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:110:in `run_with_threads'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:95:in `top_level'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:73:in `block in run'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:160:in `standard_exception_handling'
/app/vendor/bundle/ruby/1.9.1/gems/rake-10.0.4/lib/rake/application.rb:70:in `run'
Tasks: TOP => db:migrate
(See full trace by running task with --trace)

I took a look at your code, and ran the database migrations on an empty database. Your migrations seem to be fine. However, this line in your error:

PG::Error: ERROR:  relation "users" already exists

suggests that you might not be working from a fresh database. Assuming you don't have any data that's mission-critical stored in your database, your best bet is just to drop the database and start over. So, if you run:

heroku pg:reset blog_production

(assuming you're deploying in production mode) you'll have a fresh database. Then just do:

heroku run rake db:migrate

and you should be back on track.